Common randomness and secret key generation with a helper

摘要

Summary form only given. We consider the generation of commonrandomness (CR), secret or not secret, by two user terminals with aidfrom a “helper” terminal. Each terminal observes a differentcomponent of a discrete memoryless multiple source. The helper aids theusers by transmitting information to them over a noiseless publicchannel subject to a rate constraint. Furthermore, one of the users isallowed to transmit to the other user over a public channel under asimilar rate constraint. We study the maximum rate of the CR which canbe thus generated, and also under additional secrecy conditions when itmust be concealed from an eavesdropper and from a wiretapper.Single-letter capacity formulae are obtained for several special casesof interest. Connections are shown between CR capacity andidentification capacity in specific situations